test look-behind, '}' so succeeds
test look-ahead, '[' also succeeds
code block encountered, execute
advance pointer one place

##</code><code>##

advance pointer the length of the match

##</code><code>##

test look-behind, '}' so succeeds
test look-ahead, '[' also succeeds
code block encountered, execute
same match? no, continue
advance pointer the length of the match (0)

test look-behind, '}' so succeeds
test look-ahead, '[' also succeeds
code block encountered, execute
same match? yes, backtrack